The present invention relates to a phase change memory, enabling to record, delete, rewrite and reproduce information, with using the phase change.
As is described in the following Non-Patent Document 1, in accordance with a phase change recording method, write-in is conducted for information, with using the fact that a material of the recoding film or layer thereof causes the phase change, i.e., between the crystal phase and the amorphous phase, while read-out is conducted through determination on made on whether it is the crystal phase or the amorphous phase. In case when using a recording film material, such as, chalcogenide (for example, a material group of GeSbxTey), which is mostly applied in this method, because of a low stability of the amorphous phase, it is sometimes crystallized with the passage of time. Such the drawback is more serious, in particular, under the environment or circumstance of high temperature. And, as is also described in the document mentioned above, in case where the coefficient is large, in particular, about voluminous variation between crystal phase/amorphous phase, there is also a drawback that the characteristics thereof are deteriorated due to repetition of the rewriting. In this document, it is described that the higher in the lattice defect density of the composition, the smaller in the voluminous variation thereof, and therefore that it is high in the tolerance or durability against the repetition. Further, as was also described in the Non-Patent document 1, an important problem to be solved is an increase of a rewriting speed, by speeding up the speed of phase changing.
Non-Patent Document 1: “Applied Physics” Vol. 1, No. 5 (2002), from page 562 to page 565.